Because these tests restart a shard in queryableBackupMode, they must provide the shardIdentity document for the restarted shard to use through the overrideShardIdentity startup parameter.
However, this parameter must be passed through a yaml configuration file (by design).
Since the shardIdentity document must contain a valid config connection string, we need to add a workaround to either:
1) be able to know before-hand what the config connection string will be, and create a dummy yaml config file in jstests/libs, OR
and point the restarted shard to the yaml config file.